docs: def insert_into_graph(self, graph):
          """Insert this edge into a BEL graph.
  
          :param pybel.BELGraph graph: A BEL graph
          """
          u = self.source.as_bel()
          v = self.target.as_bel()
  
          if self.evidence:
              return graph.add_qualified_edge(u, v, **json.loads(self.data))
          else:
              return graph.add_unqualified_edge(u, v, self.relation)